Start using Symfony in 10 minutes! This chapter will walk you through the most
important concepts behind Symfony and explain how you can get started quickly
by showing you a simple project in action.

If you've used a web framework before, you should feel right at home with
Symfony. If not, welcome to a whole new way of developing web applications.

The only technical requisite to follow this tutorial is to have PHP 5.4 or higher
installed on your computer. If you use a packaged PHP solution such as WAMP,
XAMP or MAMP, check out that they are using PHP 5.4 or a more recent version.
You can also execute the following command in your terminal or command console
to display the installed PHP version:

This command downloads a file called symfony.phar which contains the Symfony
installer. Save or move that file to the directory where you create the Symfony
projects and then, execute the Symfony installer right away with this command:

This tutorial leverages the internal web server provided by PHP to run Symfony
applications. Therefore, running a Symfony application is a matter of browsing
the project directory and executing this command:

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$ cd myproject/
$ php app/console server:run

Open your browser and access the http://localhost:8000 URL to see the
Welcome page of Symfony:

Congratulations! Your first Symfony project is up and running!

Note

Instead of the welcome page, you may see a blank page or an error page.
This is caused by a directory permission misconfiguration. There are several
possible solutions depending on your operating system. All of them are
explained in the Setting up Permissions
section of the official book.

When you are finished working on your Symfony application, you can stop the
server with the server:stop command:

One of the main goals of a framework is to keep your code organized and to allow
your application to evolve easily over time by avoiding the mixing of database
calls, HTML tags and other PHP code in the same script. To achieve this goal
with Symfony, you'll first need to learn a few fundamental concepts.

When developing a Symfony application, your responsibility as a developer is to
write the code that maps the user's request (e.g. http://localhost:8000/)
to the resource associated with it (the Welcome to Symfony! HTML page).

The code to execute is defined in actions and controllers. The mapping
between user's requests and that code is defined via the routing configuration.
And the contents displayed in the browser are usually rendered using templates.

When you browsed http://localhost:8000/ earlier, Symfony executed the
controller defined in the src/AppBundle/Controller/DefaultController.php
file and rendered the app/Resources/views/default/index.html.twig template.
In the following sections you'll learn in detail the inner workings of Symfony
controllers, routes and templates.

In Symfony applications, controllers are usually PHP classes whose names are
suffixed with the Controller word. In this example, the controller is called
Default and the PHP class is called DefaultController.

The methods defined in a controller are called actions, they are usually
associated with one URL of the application and their names are suffixed with
Action. In this example, the Default controller has only one action
called index and defined in the indexAction method.

Actions are usually very short - around 10-15 lines of code - because they just
call other parts of the application to get or generate the needed information and
then they render a template to show the results to the user.

In this example, the index action is practically empty because it doesn't
need to call any other method. The action just renders a template with the
Welcome to Symfony! content.

Symfony routes each request to the action that handles it by matching the
requested URL against the paths configured by the application. Open again the
src/AppBundle/Controller/DefaultController.php file and take a look at the
three lines of code above the indexAction method:

These three lines define the routing configuration via the @Route() annotation.
A PHP annotation is a convenient way to configure a method without having to
write regular PHP code. Beware that annotation blocks start with /**, whereas
regular PHP comments start with /*.

The first value of @Route() defines the URL that will trigger the execution
of the action. As you don't have to add the host of your application to the URL
(e.g. `http://example.com), these URLs are always relative and they are usually
called paths. In this case, the / path refers to the application homepage.
The second value of @Route() (e.g. name="homepage") is optional and sets
the name of this route. For now this name is not needed, but later it'll be useful
for linking pages.

Considering all this, the @Route("/", name="homepage") annotation creates a
new route called homepage which makes Symfony execute the index action
of the Default controller when the user browses the / path of the application.

Tip

In addition to PHP annotations, routes can be configured in YAML, XML or
PHP files, as explained in the Routing chapter of the Symfony book.
This flexibility is one of the main features of Symfony, a framework that
never imposes a particular configuration format on you.

The $this->render() method is a convenient shortcut to render a template.
Symfony provides some useful shortcuts to any controller extending from the
Controller class.

By default, application templates are stored in the app/Resources/views/
directory. Therefore, the default/index.html.twig template corresponds to the
app/Resources/views/default/index.html.twig. Open that file and you'll see
the following code:

Now that you have a better understanding of how Symfony works, take a closer
look at the bottom of any Symfony rendered page. You should notice a small
bar with the Symfony logo. This is the "Web Debug Toolbar", and it is a
Symfony developer's best friend!

But what you see initially is only the tip of the iceberg; click on any of the
bar sections to open the profiler and get much more detailed information about
the request, the query parameters, security details, and database queries:

This tool provides so much internal information about your application that you
may be worried about your visitors accessing sensible information. Symfony is
aware of this issue and for that reason, it won't display this bar when your
application is running in the production server.

How does Symfony know whether your application is running locally or on a
production server? Keep reading to discover the concept of execution environments.

An Environment represents a group of configurations that's used to run
your application. Symfony defines two environments by default: dev
(suited for when developing the application locally) and prod (optimized
for when executing the application on production).

When you visit the http://localhost:8000 URL in your browser, you're executing
your Symfony application in the dev environment. To visit your application
in the prod environment, visit the http://localhost:8000/app.php URL instead.
If you prefer to always show the dev environment in the URL, you can visit
http://localhost:8000/app_dev.php URL.

The main difference between environments is that dev is optimized to provide
lots of information to the developer, which means worse application performance.
Meanwhile, prod is optimized to get the best performance, which means that
debug information is disabled, as well as the Web Debug Toolbar.

The other difference between environments is the configuration options used to
execute the application. When you access the dev environment, Symfony loads
the app/config/config_dev.yml configuration file. When you access the prod
environment, Symfony loads app/config/config_prod.yml file.

Typically, the environments share a large amount of configuration options. For
that reason, you put your common configuration in config.yml and override
the specific configuration file for each environment where necessary:

Congratulations! You've had your first taste of Symfony code. That wasn't so
hard, was it? There's a lot more to explore, but you should already see how
Symfony makes it really easy to implement web sites better and faster. If you
are eager to learn more about Symfony, dive into the next section:
"The View".